Huygens Probe Lands on Titan

WillDraven writes "CNN, NASA and the ESA are reporting that the Huygens space probe has entered the atmosphere of Saturn's moon Titan after traveling 2.2 billion miles. Pictures from the moon's surface should be available sometime this afternoon" according to the NASA TV schedule. What we know so far is that Huygens landed successfully and sent at least the carrier signal from the surface to Cassini for 90+ minutes, more than expected, and that Cassini has successfully repointed at the Earth and begun relaying the data it received, beginning with test packets. Huygens now sits on Titan, silent forever, while we wait to see whether or how much valuable data Cassini obtained and can send back. Update: 01/14 17:20 GMT by M : So far: they report zero lost packets in the transmission, but one of the two independent data-collection systems is apparently giving some problems. Update: 01/14 21:40 GMT by J : The news is pretty much all good: a very successful mission. Expect to see many photos within hours, but for now apparently only three have been released. Ice blocks or rolling stones -- let the debates begin!

Re:Any pics yet?

[dtolman]

Spaceflightnow.com indicates that they are now recieving data - so we could be getting the goods as early as this afternoon...

Minor explanation

[Cyclotron_Boy]

They didn't stop recording data because Huygens went silent. Rather, Cassini had to turn to transmit its load of data. Cassini had to turn for a number of reasons ranging from the azimuth and elevation of the lander (now it is more than a probe...) with respect to the horizon, to the maximum data storage capability of Cassini itself. Not that the poster said anything wrong, it was just misleading. I believe Huygens was still transmitting at least carrier verified by Colorado (not sure which radiotelescope picked it up in the US) after Cassini was tasked to turn away. We just couldn't listen much longer, and Huygens' batteries weren't supposed to do more than 4.5 hours anyway (IIRC).
-F

Re:Regarding the permanent silence of Huygens...

[FortKnox]

Two reasons:
1.) Its antenna is only strong enough to send signals to cassini, and cassini only 'see' Huygens for so long before it sets over the Titan planet.
2.) Its battery life is very short (because they knew they'd only have such a short time to transmit the data to cassini).

The planet IS harsh (like -290F), but its built to survive it long enough to talk to Cassini until it sets.

GO ESA!

[segal_loves_pandas]

This part is an European Space Agency project. You can find out more at: http://www.pparc.ac.uk/Nw/cassini_huygens.asp There is a link to the ESA/PPARC webcast there too. (PPARC is th British Research Council for Particle Physics and Astronomy.

images to be posted at ...

[MoobY]

The images will be posted from the moment they are available at

http://www.lpl.arizona.edu/%7Ekholso/data.htm [arizona.edu]

Re:First Data Recieved via Cassini!

[Anonymous Coward]

For all of you that can't read binary (who shouldn't be at /. anyway) you can refer to this website for the conversion: http://binary.viderian.com/ [viderian.com]

Re:Minor explanation

[Anonymous Coward]

The main reason that it stopped when it did was that cassini went below the horizon with respect to huygens, making it impossible to relay. It was always planned this way, since the only way to get a longer window would be for cassini to burn ALOT of fuel (probably more than it's carrying), and enter titan orbit. We may see a carrier signal from huygens well after the data relay window is over, but huygens doesn't have the transmitting power to get real data directly to earth without the relay.

Re:First Data Recieved via Cassini!

[REBloomfield]

real men don't miss a 0 out :) see 6th char...

Re:Regarding the permanent silence of Huygens...

[Anonymous Coward]

Beagle 1 was a ship. The ship Charles Darwin used to travel to the Galapagos Islands.

http://www.aboutdarwin.com/

Re:Congrats to the ESA

[slungsolow]

Here is a page with the examples of the image output.

http://www.lpl.arizona.edu/~kholso/test_images.htm [arizona.edu]

Pretty neat.

Re:Minor explanation

[Cyclotron_Boy]

Correction: Since the internal temperature of the probe has been recorded as 25 degrees C (while outside the probe is much colder), the batteries could last as long as 7 hours. However, the transmitter onboard isn't strong enough to get data to Earth directly without a relay (like Mars Orbiter for the Mars Rovers).

Re:For the record...

[jamie]

In fact that's how we first knew that Huygens had descended and landed safely -- its carrier signal to Cassini was actually picked up by a radio telescope here on Earth. That carrier was received on Earth for hours after Huygens landed!

It's there

[Anonymous Coward]

Finally, a news release from ESA:
http://www.esa.int/esaCP/SEMQ1QQ3K3E_index_0 .html

Re:stupid hippies avoiding danger

[maynard]

Citations please.

I'm not technically competent to argue the safety risks. I do think the debate is worth engaging, and I definitely think using terms like "stupid hippies" to define those arguing in the opposition helps no one understand the deeper issues. So, your references: the Wikipedia article [wikipedia.org] on plutonium appears to debunk the statement "most toxic sumstances known to man" by comparing plutonium to highly toxic organics like boltulism among others. I assume it's an LD50 comparison.

All isotopes and compounds of plutonium are toxic and radioactive. While plutonium is sometimes described in media reports as "the most toxic substance known to man", there is general agreement among experts in the field that this is incorrect. As of 2003, there has yet to be a single human death officially attributed to plutonium exposure. Naturally-occurring radium is about 200 times more radiotoxic than plutonium, and some organic toxins like botulism toxin are still more toxic. Botulism toxin, in particular, has a lethal dose in the hundreds of pg per kg, far less than the quantity of plutonium that poses a significant cancer risk. In addition, beta and gamma emitters (including the C-14 and K-40 in nearly all food) can cause cancer on casual contact, which alpha emitters cannot.

However, the author(s) note:

However, it must however be noted, that in contrast to naturally occuring radioisotopes such as radium or C-14, Plutonium has been manufactured, concentrated and isolated in large amounts (100s of metric tons) during the cold war for weapons production. These piles (whether in weapons form or otherwise) pose a significant toxicologic risk - not least due to the fact that there is no feasible known way to destroy them (whereas that can be easily done with biological posisons).

--M

Re:So quite posting rants on slashdot...

[evanbd]

you don't risk your own civilization to benefit science.

You don't? As best I can tell, ceasing all science and exploration efforts doesn't just risk civilization, it dooms it to stagnation and collapse.

So, you have to balance risks, be they personal, financial, or global, against the potential benefits. And in the case of Cassini, the risk was miniscule -- the rtg is designed to survive a launch vehicle failure or reentry without leaking; in fact, rtgs have crashed before (3 of them, I believe), with no leakage. In this case, given that the probability of a problem was very small, the likely result of a problem was far from catastrophic and not even remotely close to your "risking civilization" comment, and the payoff in knowledge gained is likely to be huge, I fully support the mission.

DISR images

[volcanopele1]

Images from Huygens should start to be released in a couple of hours. Look for them to show up here: http://www.lpl.arizona.edu/~kholso/

Re:Congrats to the ESA

[pedroloco]

BULLCRAP!!! Sorry to be so vehemously blunt, but as a space scientist who works with images, I'll say that there's a large number of us who find images to be of value for more than just the "gee-whiz" factor. Images are one of the primary ways we can learn about the geology of planetary bodies. Cassini is using its images of Saturn's rings to learn about ring dynamics. Images are helping the Mars rovers to navigate around obstacles. Often times, we are limited in the data we can extract from a probe by weight and power constraints on the transmitter. So, engineers have to economize on data volume. As it is, DISR (the imager on Huygens) had to look through a pile of haze to image the surface as it dropped in. A high resolution imager would have simply returned high resolution images of fog rather than crisp images of the surface. (I'm guessing here - I haven't seen the data stream coming down.) High-resolution might be great at the surface, but Huygens was designed to be an atmospheric experiemnt and was never designed to soft land on a hard surface (although there were hopes that it might as it seems to have done). Granted, I work in the planetary geology subfield, so I am biased in favor of imaging since I like to look at rocks. Particles and fields people aren't so interested in imagers. It was true that early designs for the Voyagers did not incorporate cameras. However, it was scientists who argued for the inclusion of an imager, not politicians.

Re:stupid hippies avoiding danger

[deglr6328]

Oh [sciencenews.org] really no idea what I'm talking about eh [ccnr.org]? Its been known for over half a century that alpha radiation is dangerous. Get a fucking clue and stop posting misinformation and falsehoods as if they were true.

Re:Regarding the permanent silence of Huygens...

[SharpFang]

(I know it had a timer set to "wake it up" for the descent).

Not a problem for batteries.
Toys like BQ4852Y [ti.com] can live off its own on-chip battery for 10 years, wake your hardware up anytime inbetween, then provide several essential functionalities to microcontrollers (watchdog, Power On Reset), store data just like RAM except retaining it when external power is missing, and they weight a few grams. So the "main" batteries won't lose any more than their internal leakage until the system wakes up.

Plutonium Toxicity

[caveat]

From the excellent Nuclear Weapons FAQ [membrane.com]:

Although plutonium presumably exhibits chemical toxicity like other heavy metals, this effect is insignificant (in fact, unobservable) compared to its radiotoxicity. Plutonium's toxic properties are due to the fact that it is an active alpha emitter. Alpha particles are hazardous only if they are emitted inside the body (i.e. the plutonium has been ingested).

...
Swallowing 500 mg (7 curies) of plutonium as a finely divided or soluble material can cause death from the acute exposure of the GI tract in several days to a few weeks. Inhalation of 100 mg (1.4 Ci) of plutonium as particles of optimal size for lung retention can cause death from lung edema in 1 to 10 days. An inhaled dose of 20 mg (0.28 Ci) will cause death by fibrosis in about 1 month. In doses much below these values, the chronic carcinogenic effects become the important ones.

It's not botulinum toxin, but it IS some pretty nasty stuff to have in you.

Re:stupid hippies avoiding danger

[deglr6328]

"Now if it were a gamma emitter, well that's a very different story"

Right. That's what I'm saying. It IS a gamma [lbl.gov] emitter too.

Re:I've always wondered...

[trtmrt]

You have a very detailed description of the spacecraft and the probe a the mission website [nasa.gov].

1) They don't fold out. It looks like a bigger dish you sometimes see on TV vans (I would say 1 to 1.5 meters in diameter). There is a picture on the site above of Cassini with a person standing beside it so you can get a sense of the size.

2) Nuclear. You have this explained in the link above.

3) To communicate with the spacecraft NASA uses the Deep Space Network (DSN) [nasa.gov], which is basically a bunch of large radio tellescopes that are positioned around the Earth so that they cover the whole sky.

4) Don't know about this one so I won't BS.

Planetary Society's blogging from mission control

[FleaPlus]

I'd like to point out again that Emily Lakdawalla of the Planetary Society is running a blog from Huygens mission control in Darmstadt, Germany. The blog is being updated as events happen.

I particularly enjoyed this quote from the blog:

He [John Zarnecki, the PI on the Surface Science Package] also said that it looks like the probe lasted about 147 minutes, which is 12 minutes longer than the predicted 135, but is "well within the error bars" of the predictions. However, he said this was still an early result--he didn't want to say for certain, because the members of a team had a bet on, and the number "looked suspiciously like the one I picked," Zarnecki said. ...

But, when pushed, scientists can't help doing just a little bit of speculating. That's how they work. So here are a couple of little initial tidbits of speculative potential facts that they have mentioned.

Number 1: Since the probe lasted for a really long time, it's "probably a good conclusion" that the probe landed on a solid, not a liquid surface, Lebreton said when he was pushed. Of course, that doesn't rule out John Zarnecki's "squelchy" surface prediction.

Number 2: One thing that may have helped the probe last a long time was that it appeared to stay unexpectedly warm. At an elevation of only 50 kilometers (about 30 miles) above the surface, her interior was still at a balmy 25 C (77 F), despite the outside temperature being a frigid -180 C (-290 F). Lebreton wasn't ready to say what this might mean. It could be overperformance of the spacecraft, but it could also mean a wide variety of unexpected things about the atmosphere. For those of you who like instant results, I think you'll be disappointed on an answer to this question, because after all Huygens was a mission focused almost entirely on Titan's atmosphere, so it's going to take a very long time to synthesize scientific conclusions from all of this.

Re:concern about signal quality

[xof]

See also the article of IEEE's Spectrum : "Titan calling [ieee.org]"that explains that the problem was not just Doppler effect on frequency, but a change in data rate, i.e. the duration of a bit, that mattered.

Link

[FleaPlus]

Crap, I'm an idiot and forgot the actual blog link. Here you go:

http://planetary.org/news/2005/huygens_blog.html [planetary.org]

Blog address

[SuperKendall]

People might want to know where they can read this blog - the address is here [planetary.org].

Thanks for the info though I did not know the blog existed, and it's always fun to get more intimate details than news reports or press releases can provide.

First picture released!

[BTWR]

here! [spaceflightnow.com]

CNN has initial pictures

[jd]

And the BBC is reporting that 3 floppy's worth of data (I'm guessing 4.5 megs) has been downloaded - much more than they'd expected.

Re:Planetary Society's blogging from mission contr

[Anonymous Coward]

She's on a weekly mp3 radio show, too. You can hear her dulcet tones here. [planetary.org]

Images available

[Johku]

Some images are now available here [arizona.edu]!

First photo from the surface!!!

[BTWR]

just released!!! [spaceflightnow.com]

Re:Pathetic!

[BlueEyes_Austin]

SOP for the ESA. I think they've only release a dozen images or so from Mars Express in MONTHS!

Thank Boris Smeds

[csb]

The Huygens probe was saved from probable failure, due to the inability of Cassini's receiver to compensate for the doppler effect:

Titan Calling [ieee.org] How a Swedish engineer saved a once-in-a-lifetime mission to Saturn's mysterious moon (by James Oberg)

Without this guy, things would have gone a lot differently! I found this article in RISKS digest 23.65 (always worth a read).